/Engine/Source/Runtime/Engine/Public/MaterialCachedData.h
Adds a parameter. If this returns false, a parameter with identical name has already been added but it was set to a different value.
bool AddParameter ( const [FMaterialParameterInfo](API\Runtime\Engine\FMaterialParameterInfo) & ParameterInfo, const [FMaterialParameterMetadata](API\Runtime\Engine\FMaterialParameterMetadata) & ParameterMeta, [UObject](API\Runtime\CoreUObject\UObject\UObject) *& OutReferencedTexture )